This invention relates to a process for the preparation of 24,24-difluoro-1.alpha.,25-dihydroxycholecalciferol.
Vitamin D.sub.3 or cholecalciferol is a well-known agent for the control of calcium and phosphorous homeostasis. In the normal animal or human, this compound is known to stimulate intestinal calcium transport and bone-calcium mobilization and is effective in preventing rickets.
It is also now well known that to be effective, vitamin D.sub.3 must be converted in vivo to its hydroxylated forms. For example, the vitamin is first hydroxylated in the liver to form 25-hydroxy-vitamin D.sub.3 and is further hydroxylated in the kidney to produce 1.alpha.,25-dihydroxy vitamin D.sub.3 or 24R,25-dihydroxy vitamin D.sub.3. The 1.alpha.,25-dihydroxylated form of the vitamin is generally considered to be the physiologically-active or hormonal form of the vitamin and to be responsible for what are termed the vitamin D-like activities such as increasing intestinal absorption of calcium and phosphate and mobilizing bone mineral.